Electric cars and hybrid vehicles having a motor as a driving source have been put to practical use. Electric power from a battery is boosted and converted to be supplied to the motor. Electronic components (e.g. a semiconductor element constituting an inverter) for supplying the electric power to the motor are usually accommodated in a casing and protected from the outside. In recent years, from the viewpoint of securing of space, there has been a demand for miniaturization of the casing for accommodating the electronic components for supplying the electric power to the motor. Such a technique of miniaturizing the casing is disclosed in Japanese Patent Laying-Open No. 2004-312925, for example.
Electric equipment disclosed in Japanese Patent Laying-Open No. 2004-312925 includes an inverter circuit, a case having an open upper portion and storing the inverter circuit in a lower portion, a capacitor connected to the inverter circuit, and a housing storing the capacitor. The housing storing the capacitor is connected to an upper peripheral surface of the case storing the inverter circuit. An inverter control substrate is provided between the inverter and the capacitor.
According to the electric equipment disclosed in Japanese Patent Laying-Open No. 2004-312925, the upper opening of the case storing the inverter can be closed by the housing storing the capacitor. Thus, the capacitor, the inverter circuit and the inverter control substrate can be protected from the outside without providing a member only for closing the opening of the case. Space for the member only for closing the opening of the case can thus be reduced, which leads to miniaturization of the electric equipment.
In the electric equipment disclosed in Japanese Patent Laying-Open No. 2004-312925, however, consideration is not given to an effect of a heat ray from the inverter circuit and the like upon the capacitor. Namely, the inverter circuit and a circuit mounted on the inverter control substrate generate heat through electrical conduction, and radiate a heat ray. When the emitted heat ray is absorbed into the capacitor to increase a temperature of the capacitor, performance of the capacitor may deteriorate. In particular, with a tendency toward an even shorter distance between an inverter circuit and the like and a capacitor as cases become miniaturized, the effect of a heat ray from the inverter circuit and the like upon an increase in temperature of the capacitor tends to be greater.